This application seeks support for the continuation of research into the molecular basis and cellular functions of ion transport across cell membranes. These investigations have been supported as components of a Program Project Grant (HL 12157, Principal investigator, D. C. Tosteson) to Duke University. The scientists responsible for this work are moving to the University of Chicago but support for their experiments will remain at Duke University, which intends to modify appropriately the projects supported by HL 12157. This application requests funds to sustain the experimental programs of the scientists who are moving from Duke to the University of Chicago until they have time to submit applications for new grants. The projects involve investigations of Ion Transport across Lipid Bilayer Membranes (R. Latorre, M.T. Tosteson, D.C. Tosteson), Anion Transport across Red Cell Membranes (R.B. Gunn and D. C. Tosteson) and Cation Transport across Red Cell Membranes (D.C. Tosteson and R.B. Gunn). The Bilayer work comprises studies of ion channels and ion carriers in these model systems as well as attempts to reconstitute biological membrane transport processes. The red cell work includes investigations of the mechanisms of chloride, sodium, potassium and lithium transport.